Digital content is of excellent quality and quite convenient to manage compared to conventional analog content. However, since digital content can be copied an unlimited number of times, the danger and possible extent of infringement are great. In particular, in digital broadcasting, it is well known that when easy-to-copy digital content is provided to many subscribers, wide scale copyright infringement results. Accordingly, as protection of digital content is rapidly regarded as being of great importance to the development of digital industries, various formats of digital rights management (DRM) have been developed.
As broadcasting service is digitalized, a slightly improved protection mechanism is required. A conventional conditional access system (CAS) cannot guarantee the security of broadcast content in emerging broadcasting business models. For example, it cannot guarantee protection of broadcast content from recording and re-distribution.
In a conventional broadcasting system, each of broadcasting station servers (broadcasters) uses its own specific protection mechanism for a broadcasting service, and does not have a protection mechanism compatible with other broadcasting stations. Accordingly, if an end user intends to use a new channel service from other broadcasters, he/she has to change his/her own set-top-box (STB). This is very troublesome and costly to consumers of broadcast content.
Further, in the case where the user replaces his/her set-top-box with another one, he/she should reregister the new set-top-box with each broadcasting station. This results in great inconvenience to the user.
In the meantime, a user lawfully receiving content may wish to use the received content in devices other than a multimedia device used to receive the content, or to re-distribute the received content to other users. However, the conventional art does not permit such varied license distribution. This is a limitation to the user in using the content, and may be an obstacle to the spread of digital content broadcasting.